Broach



J. OAKLEY.

' BROACH.

APPLICATION FILED JULY 9,1919.

Patented Nov. 23,1920. v

r 6 J- F 7 8f 7 f 7 INVEN TOR.

A TTORNE Y.

uniren rare-s PAT-em QFFICE.

JOHN OAKLEY, or SPRINGFIELD, MASSACHUSETTS.

BROACH.

lowing is a specification.

My invention relates to improvements in tools of thedrift or broach type, which are used to cut grooves, channels, slots, and the like in various Ob18CtS, and cons sts essentially of a shank provided with teeth, and

having depressed surface, chip-clearance passages opening at the rear end,such teeth overhanging such passages together with such other parts and members as may be needed or desired to render the tool complete and serviceable in all respects, all as hereinafter set forth.

This application is a divisional part of my application for patent of the United States, Serial No. 241,748. r I

lVith this broach the original slot in the stock may .be cut or a slot previously cut may be widened, according to the manner in which my invention is applied and the tool used.

The primary object of my invention is to produce a broach for cutting slots, in which 1 there is employed clearance tor the chips,

so that cloggingis prevented; and there is v no liability of'injuring, by chipping, slivering, or tearing the stock.

' With a tool embodying my invention I I am able to breach a wide slot w th great ac-',

curacy and high finish, and in less time than is commonly -requ1red for the same work perfoi'medwith the-old type of breaching and ages of my invention by the means illustrated in the accompanying drawings, 'wh1ch' Figure 1 is a side elevation of a broach whichembodies a practical form-of my in-- vention, the middle portion of said broach being broken out in this view and in Figs. 6

4 toe'conomize space; Fig. 2, a top plan of the front en'd portion of said broach; Fig. 3. a cross section through said broach, taken -scrib the" oach i ilz ft i t 'r ensfwhi widen ng oo sbut zmar. be

on lines 3, looking in the direction of the, as'socratedfarrow inFig. 1; Fig. 4, a l I cross section through "the broach, on lines 4 -4, looking in thesame direction as be- 'fore, Fig. 1; F 5, an end elevation of a piece of stock, illustrating the operation or purpose of said broach; Fig. 6, a top plan" of a broach which embodies another practical term of said 1nvention, and Fig. 7, a combined sideele'vatlon'of and central, lon- Specification of Letters Patent. Patented N V 23 192 Original application filed Jul 1e25, 1913, Serial No. 241,748. "Divided and this application "fi l ed July 9,

' 1919. Serial No. 309,599. i

gitudinal, verticalsectionthrough said last-.

named broach. V Y 1 S milar reference characters designate sim lar parts throughout the several 'views.

It should be noted in=.passing that the di- J ameter of each shank of thebroach is the.

same as that of the-main passage through said stock. The heights or radial depths of theteeth of either of these broaches increase from front to rear,-as is the case with the teeth of ordinary breaches.

the stock, and the width 0t each tooth or of v Usually the teeth be attachable to and detachable from rather than integral with the shank. In the' event the broach; is

designed to widen a slot already cut, said broach ispreferably provided with a pilot or q iva n mea f idi e t et I In the ma r f har Zaa rang me t' and construction of the parts of-my invenfltis t be und ood. h othe mo fications, in additionto these illustrated in connection herewith, may b'e. made without depart ng from the nature Of$2L1Cl invention orexceeding the scope oi; what -is claimed, wherefore I do not desire or intend to be strict to h t o e nh d me t flher shown anddes ribe i ste lliete r-ing to-th igs- Wil ii nsed'forthe or ginal rili al l l t lligef v i eis t' as w presen ly be m re clear y-c expl ned; nd then d scribe th broa h in ig .6 and 51, w ch sieqilippe w th na witho u hlev s ra onath to or inju ious actiononjthe stock. 5 r

I desire, first, to can iattentibi to the fact that each broach comprises a shank 1, which is provided at' jthe forward or 'leading terminal with suitable means for attaching said broach to the machine, as screwthreaded puller-head 2, the same i being partly broken off in Figs. 6 and 7, and a plurality of teeth, which latter are radially cutting inthe examples hereinv shown.

6. The front edge of each tooth 5 is undercut or beveled from the outside inward and rearward to form of the front, outer edge of said tooth a cutting edge 7 Two longitudinal chip-clearance passages or channels 8 are formed in the shank 1, one on each side of that part of'said shank to which the teeth 5 are directly secured by the'screws 6. The channels 8 are cut into the side of the shank and extend from points in advance of the transverse plane of said shank in which is located the foremost cutting edge 7 hang the channel 8 on botlrsides.

to the'rear end said shank, through which end said channels open. The teeth 5 over- Said teeth, as shown, are all of the same thickness and let into the shank 1 in such a manner as to obtain the stepped arrangement required in breaching, the foremost tooth 1 being set in the most, the next being set in shank and plug.

not quite so far, the third less, and so on, the rearmost tooth being set in the least of all. A pilot 9, of the same width and depth as the width and depth of the slot which this tool is designed to widen, is located on the shank 1 in advance of the row of teeth 5 and in the central, longitudinal plane of said row. The pilot is formed on the outer end of a plug 10 which fits within a recess in the shank, and is secured therein by a transverse pin 12 passing through said The central portions of" the cuttlng edges ,-wh1ch are in direct line with the pilot 9, do no cutting, but" the out lying portions of said'edges cut away they stock to widen the original slot. It is plainly to be seen, then, that the chips cut by the teeth 5 must pass directly into the' channels 8 and through the latter to escape at the rear end of the shank. That part of the shank 1 which directly supports the teeth 5 is no wider that the pilot 9, consequently there is nothing to divert the chips fromtheir courses against the beveled front' cut, and into the channels 8.

edges of saidteeth, as soon as said chips are The outer faces of the teeth 5 are beveled slightly for clearance-as usual, and the same thing is true of the teethin the other example of broach shown in connectionherewith.

Assuming now that a piece of stock 13,"

" Fig. 5, has a central opening or passage 1 1.

and a slot 15 therethrough, which slot it is desired. to widen, and that the shank 1 of the broach just described will fit said passage and the pilot 9 of said broach will fit said slot, while the width of the teeth of said broach corresponds with the width of the required slot, and the depth of the rearmost tooth is equal to the depth of the slot, the operation of widening is as follows: The forward end of the shank 1 is introduced into the passage 14 and the'pilot 9 into the slot 15, and the tool is drawn forcibly through said slot, with the result that the cutting edges 7 or the portions thereof that overhang the channels 8 progressively cut away the inner periphery of the stock both sides of said slot, as indicated by broken lines in Fig. 5, forming first the inner corners of the enlarged or widened,

slot and working radially or outwardly until finally the wide slot complete is produced. Owing to the fact that the first few cuts in the widening operation are on chords of the opening 145, the teeth 5 which make said cuts must be depressed so much that their cutting edges 7 arebelowthe periphery of the shank 1.

The pilot 9 leads and the teeth 5 follow and cut the slot the full width and deeper V and deeper the farther the tool progresses, as is clearly apparent. The chips cut by the teeth 5 on both sides of the slot are directed by the beveled front edges of saidy teeth into the passages or channels and finally oil at the back end of the tool.

Passing next to the second broach, that shown in Figs. 6 and 7, it will be seen that this broach has alternately arranged narrow teeth 17 and wide teeth 5. By providing the broach with the narrow and wide teeth, I am able to cut a wide slot with the single tool expeditiously, accurately, and with comparative ease. The teeth 17 are received in transverse passages 18 in the shank 1, they are secured with transverse pins 19, and said passages open at one end through the top or one side of said shank, and at the outer end into a longitudinal passage 20 in said shank, all as fully set forth in United States Letters Patent No. 1,272,841, while the teeth 5 aremounted on the shank and secured with the screws 6, as in the first instance, The teeth 17 have cutting edges 21 at the outer end of their front edges. One

of the teeth 17 leads, then follow in a row the teeth 5 and 17 arranged alternately, until the rear end of the shank is reached where there are two teeth 5 instead of only one. The cutting edge 7 of each'tooth 5, with the exception of the cutting edge of the rearmost tooth 5,.projects less than the cutting edge 21 of the tooth 17 immediately in front, for the'reason that, during the first part of the cutting operation" the chord in,

the bore of the stock which corresponds with or represents the width of the cut of the wide tooth is longer than the chord in said bore which corresponds with or represents the width of the cut of the narrow tooth. If the first narrow and the first wide cutting edges were on the same plane parallel with the longitudinal center of the shank, the second narrow and the second wide cutting edges on the same plane parallel with the said center, and so on, the wide cutting edges might be required to make cuts which would be too deep to be practicable. The difference in depth of out between each narrow tooth'andthe wide tooth immediately behind is compensated for bythe addition of the extra, wide tooth at the rear end, which tooth has a cutting edge that is level with the cutting edge of the rearmost narrow tooth.

When the second broach is in use the foremost tooth 17 first makes a narrow cut in the stock, then the foremost tooth 5 makes a wide out which is nearer the axial center of the shank than is the initial cut, next the 1 second tooth 17 cuts a little deeper the width until the latter is completed throughout itsentire length. 7

The cutting edge 21 of each tooth 17 proj ects a trifle less than such edge of the tooth 17 immediately behind, of course, and so, also, with the associated teeth 5 and their cutting edges 7.

Although the lands between the channels 8 in which the teeth 17 are located extend under or beyond the inner edge portions of V the chips cut by the teeth 5 said chips readily pass over such lands into said'channels, owing to the fact that the lands are convex and considerable portions of said teeth extend over said channels.

It is an advantage 'to employ attachable and detachable teeth, and an attachable and detachable pilot where used, not only because it is frequently less expensive to construct a broach with such attachable and 4 detachable members, but on account of the fact that such members when damagedor broken can be taken out, repaired, and replaced, or replaced with new ones, without being obliged to discard the entire broach- The manner of removing and replacing any of the teeth and the pilot will be readily understood from the drawings and hereinbefore given description.

It is also plainthat it is necessary to pro vide the depressed-surface, clearance passages or channels within or inside oithe major diameter and opening at the rear end of the shank, for the chips cut by the front edges of the teeth, 1n each case.

lVhat I claim as my invention, and desire to secure by Letters Patent, is-

1. A broach comprising a shank having longitudinal channels formed in the periphery and opening at the rearend of said shank, and a row of teeth mounted on that part of said shank which is between said channels, and extending over the latter.

2. A broach comprising a shank having longitudinal channels formed in the periphery and opening at the rear end of said shank, and alternately arranged narrow and wide teeth mounted on said shank, the wide teeth extending over said channels.

A broach comprising a longitudinally channeled shank and a row of teeth mounted onand extending over the channeled portion of said shank.

4. A broach comprising a shank, and teeth I separate from said shank, and means to attach said teeth to said shank, the latter hav ing depressed surface clearance passages within the major diameter and'opening at the rear of said shank, to receive the chips teeth extending cut by said teeth, and said over such passages.

JOHN OAKLEY.

Witnesses:

F. A. CUTTER, A. C. FAIRBANKS. 

